Differences between false-negative and true-positive Papanicolaou smears on Papnet-assisted review

This study explored whether there were differences between false-negative and true-positive Papanicolaou (Pap) smears in the number of abnormal images on a Papnet-assisted review. The degree of agreement between cytotechnologists over Papnet tile status (normal/abnormal) was assessed. False-negative and true-positive Pap smears preceding a histologic diagnosis of carcinoma in situ were scanned by Papnet, and the resulting digital images and slides were assessed independently by three cytotechnologists. The median number of abnormal tiles was 7.3 for false-negative slides and 29.7 for true-positive slides. Three-way agreement between cytotechnologists was better for true-positive slides (kappa, 0.60) than for false-negative slides (kappa, 0.47). These results confirm intrinsic differences between false-negative and true-positive Pap smears. The fair to good agreement beyond chance on tile status indicates that a cautious approach should be adopted if digital image review is performed in a judgemental manner.